Efficacy of Prussian blue on 137Cs decorporation therapy.

Prussian blue (PB) is an efficient drug for enhancing cesium elimination from the body. Literature data on the efficacy of PB treatment in dosages that vary from 1-10 g d was reviewed. Cesium biokinetics was simulated using a detailed systemic biokinetic model. The same model was used to simulate the maximum action of PB by interrupting the enterohepatic circulation. Model results reproduced reasonably well the literature data on the efficacy of PB administered to humans after incidental cesium intakes, as well as results from animal experiments. Maximum efficiency of the reduction of the long-term half-time is obtained with the administration of 3 g d PB to the adult. Maximum efficiency of reducing the Cs body burdens is obtained when PB is administered on the first day after the intake, due to the increase of the short-term elimination of cesium. The model predicts that reduction of the long-term half-life is not affected by the time after intake that PB is administered, as long as it is given within the interval from 1 h to 1 y after the intake.

A mobile bioassay laboratory for the assessment of internal doses based on in vivo and in vitro measurements.

Internal exposures may occur in nuclear power plants, radioisotope production, and in medicine and research laboratories. Such practices require quick response in case of accidents of a wide range of magnitudes. This work presents the design and calibration of a mobile laboratory for the assessment of accidents involving workers and the population as well as for routine monitoring. The system was set up in a truck with internal dimensions of 3.30 m × 1.60 m × 1.70 m and can identify photon emitters in the energy range of 100-3,000 keV in the whole body, organs, and in urine. A thyroid monitor consisting of a lead-collimated NaI(Tl)3" × 3" (7.62 × 7.62 cm) detector was calibrated with a neck-thyroid phantom developed at the IRD (Instituto de Radioproteção e Dosimetria). Whole body measurements were performed with a NaI(Tl)8" × 4" (20.32 × 10.16 cm) detector calibrated with a plastic-bottle phantom. Urine samples were measured with another NaI(Tl) 3" × 3" (7.62 × 7.62 cm) detector set up in a steel support. Standard solutions were provided by the National Laboratory for Metrology of Ionizing Radiation of the IRD. Urine measurements are based on a calibration of efficiency vs. energy for standard volumes. Detection limits were converted to minimum committed effective doses for the radionuclides of interest using standard biokinetic and dosimetric models in order to evaluate the applicability and limitations of the system. Sensitivities for high-energy activation and fission products show that the system is suitable for use in emergency and routine monitoring of individuals under risk of internal exposure by such radionuclides.

AIDE: internal dosimetry software.

AIDE (Activity and Internal Dose Estimates) is a software for calculating activities in compartments and committed doses due to occupational exposures, and for performing intake and dose estimates using bioassay data. It has been continuously developed and tested for more than 20 years. Its calculation core has been applied in several situations, like performing all dose estimates due to (137)Cs intakes, which occurred during the Goiania accident in 1987; performing quality assurance of the ICRP Task Group on Dose Calculations regarding calculations of activities in compartments and generation of dose coefficients for adults due to intakes by inhalation, ingestion and injection of several radionuclides; and producing the tables of activities in compartments and dose coefficients using the NCRP Wound Model for the NCRP report. It provides several capabilities like performing calculations using modified Human Respiratory Tract Model parameters for the mechanical transport, blood absorption and partitions of deposit in the AI region. The existing systemic models can also be modified or new ones can be entered. All estimate procedures are in accordance with the methods presented in the ICRP-78 Publication, in the IAEA Safety Reports Series no. 37 and in the IDEAS Project Guidelines 2006.

Methylmalonate inhibits succinate-supported oxygen consumption by interfering with mitochondrial succinate uptake.

The effect of methylmalonate (MMA) on mitochondrial succinate oxidation has received great attention since it could present an important role in energy metabolism impairment in methylmalonic acidaemia. In the present work, we show that while millimolar concentrations of MMA inhibit succinate-supported oxygen consumption by isolated rat brain or muscle mitochondria, there is no effect when either a pool of NADH-linked substrates or N,N,N',N'-tetramethyl-p-phenylendiamine (TMPD)/ascorbate were used as electron donors. Interestingly, the inhibitory effect of MMA, but not of malonate, on succinate-supported brain mitochondrial oxygen consumption was minimized when nonselective permeabilization of mitochondrial membranes was induced by alamethicin. In addition, only a slight inhibitory effect of MMA was observed on succinate-supported oxygen consumption by inside-out submitochondrial particles. In agreement with these observations, brain mitochondrial swelling experiments indicate that MMA is an important inhibitor of succinate transport by the dicarboxylate carrier. Under our experimental conditions, there was no evidence of malonate production in MMA-treated mitochondria. We conclude that MMA inhibits succinate-supported mitochondrial oxygen consumption by interfering with the uptake of this substrate. Although succinate generated outside the mitochondria is probably not a sig-nificant contributor to mitochondrial energy generation, the physiopathological implications of MMA-induced inhibition of substrate transport by the mitochondrial dicarboxylate carrier are discussed.

Review of standards of protection for pregnant workers and their offspring.

The recommendations of the International Commission on Radiological Protection and the IAEA Basic Safety Standards (BSS) make clear that the embryo and fetus should be regarded as a member of the public when considering the protection of female workers who are or may be pregnant. The BSS note that the embryo and fetus should be 'afforded the same broad level of protection as required for members of the public'. Similar guidance is included in national legislation in a number of countries. On the basis of a review of such guidance, it was concluded that although the recommendations provided in the BSS are in general agreement with the international consensus on approaches to the protection of pregnant workers and their offspring, more specific supporting guidance is needed. The IAEA is preparing a technical document that extends and clarifies previous advice and considers the practical application of the advice for workers in different types of workplace, for which important potential routes of exposure for the pregnant worker have been identified. This action is being carried out under the framework of the International Action Plan for Occupational Radiation Protection.

Efeitos de Beauveria bassiana (Bals) Vuill e Metarhizium anisopliae (Metsc) Sorok sobre fêmeas ingurgitadas de Amblyomma cajennense (Fabricius, 1787) em condições de laboratório / Effects of Beauveria bassiana (Bals) Vuill and Metarhizium anisopliae (Metsc) Sorok on engorged females of Amblyomma cajennense (Fabricius, 1787) in laboratory conditions

The in vitro susceptibility of Amblyomma cajennense engorged females to some isolated of the fungus Beauveria bassiana and Metarhizium anisopliae was verified and lethal concentrations (LC 50 and LC 90) were calculated. The females were dived in conidia suspensions for five minutes, and kept in climatically controlled chambers BOD under 27º C and 80 por cento relative humidity. Each bioassay had four treatments in concentrations of 105,106,107 e 108 conidia/ml. A control group was also used. The following characteristics were evaluated: weight and period of oviposition, indexes of reproductive and nutritional efficiency and percentage of microbiological control. A dose dependent negative effect was observed in ticks treated with the suspension. All isolates tested cause a negative effect on in vitro tests of engorged females of A. cajennense, suggesting its potential for microbiological control of tick's species.

A physiologically based biokinetic model for cesium in the human body.

A physiologically descriptive model of the biological behavior of cesium in the human body has been constructed around a detailed blood flow model. The rate of transfer from plasma into a tissue is determined by the blood perfusion rate and the tissue-specific extraction fraction of Cs during passage from arterial to venous plasma. Information on tissue-specific extraction of Cs is supplemented with information on the Cs analogues, K and Rb, and known patterns of discrimination between these metals by tissues. The rate of return from a tissue to plasma is estimated from the relative contents of Cs in plasma and the tissue at equilibrium as estimated from environmental studies. Transfers of Cs other than exchange between plasma and tissues (e.g. secretions into the gastrointestinal tract) are based on a combination of physiological considerations and empirical data on Cs or related elements. Model predictions are consistent with the sizable database on the time-dependent distribution and retention of radiocesium in the human body.

NORM workers: a challenge for internal dosimetry programmes.

The mining, milling and processing of uranium and thorium bearing minerals may result in radiation doses to workers. The control of occupational exposures from these natural sources of radiation imposes a challenge to regulators and radiation protection advisers. A survey pilot programme, which included six mines in Brazil and a monazite plant, was established, consisting of the collection and analysis of concentrations of uranium, thorium and polonium in urine, faeces and air samples. Results from workers were compared to background data from their families living in the same area and from residents from the population of Rio de Janeiro. Positive exposure results were identified among the coal miners, the niobium miners and the monazite sand workers. Difficulties in the application of internal dosimetry programmes are discussed in relation to the control of NORM workers.

Requirements for authorisation of internal dosimetry services.

In order to ensure that a facility is in compliance with the occupational exposure requirements established by regulatory authorities, the measurements and dose assessments specified in the individual monitoring programme need to be reliable. There are two important questions that shall be addressed here: one is how the licensed facilities can demonstrate to their workers and regulatory bodies compliance with the regulatory limits and the reliability of the results of the individual monitoring programmes; the other concerns the mechanisms used to demonstrate to a facility in another country the reliability of the measurement results of an individual monitoring bioassay programme. The accreditation of the bioassay laboratory, according to ISO/IEC 17025, shall be the basic requirement for obtaining the authorisation granted by the national regulatory authority. For the second question, such confidence can be achieved through International Laboratory Accreditation Cooperation (ILAC).

Açäo in vitro dos fungos Beauveria bassiana (Bals) Vuill e Metarhizium anisopliae (Metsch) Sorok sobre ninfas e adultos de Amblyomma cajennense (Fabricius, 1787) (Acari: Ixodidae) / In vitro of the fungi Beauveria bassiana (Bals) Vuill and Metarhizium anisopliae (Metsch) Sorok on ninphs and adults of Amblyomma cajennense (Fabricius, 1787) (Acari: Ixodidae)

O trabalho teve por objetivo verificar a mortalidade in vitro de ninfas e adultos de Amblyomma cajennense frente à açäo de isolados dos fungos Beauveria bassiana e Metharhizium anisopliae. Foram avaliados três isolados de M. anisopliae (959, 319 e E9) e dois de B. bassiana (986 e 747). As suspensöes de conídios foram preparadas a partir de fungos produzidos em meio de arroz, e cada bioensaio foi constituído de quatro tratamentos nas concentraçöes 10 elevado a 5, 10 elevado a 6, 10 elevado a 7, 10 elevado a 8 conídios/ml e um grupo-controle. A análise constou da observaçäo do percentual de mortalidade, 15 dias após o tratamento ou após a ecdise de adultos. Foram observadas diferenças significativas entre os tratamentos quanto à mortalidade para todos os isolados e todos os instares. Nos grupos tratados houve aumento considerável na mortalidade à medida que se aumentava a concentraçäo de conídios na suspensäo. Conclui-se que todos os isolados testados causaram mortalidade em testes in vitro sobre esses estádios evolutivos, sugerindo o controle do A. cajennense pela açäo desses fungos

Exposure of workers in mineral processing industries in Brazil.

The mining, milling and processing of uranium and thorium bearing minerals may result in radiation doses to workers. A preliminary survey pilot program, that included six mines in Brazil (two coal mines, one niobium mine, one nickel mine, one gold mine and one phosphate mine), was launched in order to determine the need to control the radioactive exposure of the mine-workers. Our survey consisted of the collection and analysis of urine samples, complemented by feces and air samples. The concentrations of uranium, thorium and polonium were measured in these samples and compared to background data from family members of the workers living in the same dwelling and from residents from the general population of Rio de Janeiro. The results from the coal mines indicated that the inhalation of radon progeny may be a source of occupational exposure. The workers from the nickel, gold and phosphate mines that were visited do not require a program to control internal radiological doses. The niobium mine results showed that in some areas of the industry exposure to thorium and uranium might occur.

A biokinetic model for 137Cs.

An improved biokinetic model for 137Cs in humans was developed based on an analysis of data obtained from individuals internally contaminated during an accident in Goiania, Brazil, and other data. Seventeen children (ten girls and seven boys 1-10 y old), ten adolescents (four females and six males), and thirty adults, (fifteen females and fifteen males contaminated in the accident in Goiânia contributed to this study. 137Cs retention was determined through periodic measurements in a whole-body counter. In addition to the data on 137Cs retention from these individuals, data from a study on the metabolism of 137Cs in immature, adult, and aged Beagle dogs and data from the literature were used in the formulation of the 137Cs biokinetic model presented. Mathematically, the retention of cesium is described by three exponential terms, and the retention model is based on a step function of body weight. When the ICRP Publication 56 model for cesium was compared to the model suggested in this paper, it was determined that the ICRP model predicts lower effective doses in 5-y-old children and higher effective doses in infants, adolescents, and adults.

Radiation protection : Medical aspects of the Goiania accident individual monitoring

In September 1987, the rotating asembly of the shielding head of a Teletheraphy unit was removed and the capsule containing 50.9 TBq of 137Cs was dismantled resulting in the widespread contamination of the central Goiania city. This accident resulted in the external and internal exposure of several people, of both genders and of ages ranging from newborn to 73 years old. Sixteen days elapsed between the breaching of the source and the discovery of the accident. During this time, children and adults suffered whole body irradiation and became internally contaminated from eating with contamination hands and from contaminated utensils. People who had handled the source, who lived in houses adjacents to the contaminated sites, or who had some type of contact with the victims were referred to the stadium for monitoring. During the first two months urine and feces analysis was used to evaluate the 137Cs internal contamination and efficacy of PB on 137Cs decorporation. Goiania is located far from any radiationprotection center with the capability to perform in vivo measurements and in vitro monitoring was considering the best technique since most of the individuals had external contamination which would interfere with the in vivo monitoring results

Management of internal contamination accidents

The key to success in managing accidents is the prompt and accurate response of the emergency team. Literature data on the preparation of well conceived emergency plans for the management of internal contamination accidents include among others the following two publications: "The guidebook for the treatment of accidental internal radionuclide contamination of workers", published in Radiation Protection Dosimetry, vol. 41, 1992 and "Assessment and Treatment of External and Internal Radionuclide Contamination", IAEA-TecDoc-869, 1996. Internal contamination by radionuclides occur most likely by inhalation, ingestion or absorption from wounds. The consequences of the contamination depend upon the route of intake, on the physical and chemical properties of the radionuclide and on the amount of activity incorporated. Decisions about the treatment of internally contaminated people should only be made by physicians. The techniques to assess intakes depend on the mode and level of intake, the type and energy of the radiation emitted, the biokinetic of the contaminant and the sensitivity and availability of measurement facilities. In vivo and in vitro techniques are used to quantify internal contamination. This document explains techniques such as In vivo bioassay, In vitro techniques, In vitro bioassay and it discusses about bioassay monitoring techniques, physical samples and interpretation of results

Prussian Blue decorporation of 137Cs in beagles of different ages.

A 6-wk study was conducted using immature (4.7 mo), young adult (2.4 y), and aged (13.5 y) male beagles to determine the modifying effect of age on the effectiveness of Prussian Blue decorporation therapy for the removal of injected 137Cs. Whole-body clearance rates for injected 137Cs decreased with increasing age in the dogs. Treatment with Prussian Blue changed the ratio of fecal to urinary 137Cs excretion from 0.8 in untreated dogs to 2.2 in treated animals. The 137Cs concentrations in tissues of untreated and Prussian Blue-treated dogs at the end of the 6-wk study were similar, with the greatest concentrations in the skeletal muscle tissue, spleen, and kidneys. There was a lower concentration of 137Cs in the livers of the treated dogs. The reductions in the average total whole-body doses resulting from Prussian Blue treatment during the course of this study were 51% in the immature, 31% in the young adult, and 38% in the aged dogs. Because of the differences in the intake of Prussian Blue by the dogs in the different groups relative to their body weight, it is unclear as to the relative effectiveness of Prussian Blue in dogs of different ages.

137Cs internal contamination involving a Brazilian accident, and the efficacy of Prussian Blue treatment.

In an accident involving the stealing and breaching of a radiotherapy source in Goiânia, Brazil, 39 individuals had a high level of 137Cs internal contamination. Prussian Blue was used, in doses that varied from 3-10 g d-1 for adults, to enhance the elimination of 137Cs from the body. The total internal committed doses and the effect of Prussian Blue treatment for 15 contaminated adults involved in this accident have been evaluated in this paper. Prussian Blue caused dose reductions in the range of 51-84%, with an average of 71%. This reduction was shown to be independent of the dosage of Prussian Blue. Total internal committed doses were in the range of 4.6 x 10(-3) Gy to 9.7 x 10(-1) Gy for the most-contaminated adults. Data on 137Cs biological half-lives for seven children contaminated in the accident are also presented.

Application of in-vitro bioassay for 137Cs during the emergency phase of the Goiânia accident.

In the Goiânia accident, many individuals suffered external and internal contamination. The screening of internal contamination was done through 137Cs urinary excretion. During the first month after the accident, only in-vitro bioassay procedures were done. Incorporation into the body and committed doses were estimated using age-specific mathematical models correlating these quantities to the 137Cs excreted in urine. The ratio of feces to urine of 137Cs excretion was used to evaluate the effectiveness of the administration of Prussian Blue on removal of 137Cs from the body.